Electrochemical Corrosion Behavior Of Al_0.1CoCrFeNi High-entropy Alloy

High entropy alloy is a new type of alloy,usually includes five or more alloy elements with approximately equal molar concentrations.Its advent has provided many possibilities for researchers to explore new high-performance alloys.According to reports,high entropy alloys have many excellent mechanical and physical properties compared to traditional alloys,such as high thermal stability,high strength,high hardness,special electromagnetic properties,excellent high and low temperature properties,and excellent corrosion resistance.This makes high entropy alloys recognized as promising next-generation high-performance alloys.High entropy alloy is a new type of alloy,usually including five or more alloy elements with approximately equal molar concentrations.Its advent has provided many possibilities for researchers to explore new high-performance alloys.According to reports,high entropy alloys have many excellent mechanical and physical properties compared to traditional alloys,such as high thermal stability,high strength,high hardness,special electromagnetic properties,excellent high and low temperature properties,and excellent corrosion resistance.This makes high-entropy alloys recognized as promising next-generation high-performance alloys.Because of its unique structure involving phase structure,element interaction,composition adjustment,grain size and other research dimensions,high entropy alloys also bring new possibilities for further understanding of the corrosion mechanism of alloys.At present,the research on the corrosion mechanism of high-entropy alloys is still relatively few.In this paper,the as-cast Al_0.1Co Cr Fe Ni high-entropy alloy was prepared by using a vacuum arc melting furnace,and its corrosion behavior in acidic,neutral and chlorine-containing solutions was studied and discussed in depth using a three-electrode system.In a sulfuric acid solution,the alloy exhibits overall excellent corrosion resistance.The samples showed significant spontaneous passivation at low concentrations(0.1M,0.2M and 0.3M),and two anode activity-passivation peaks at high concentrations(0.5M and 1.0M).In addition,scanning electron microscope(SEM)studies show that selective corrosion starts from the inter-dendritic region.Further X-ray photoelectron spectroscopy(XPS)test results show that the multi-passivation behavior of the alloy is related to the change of the chemical composition of the passivation film.The possible reaction pathways of the sample during the anodic dissolution process were discussed.The adsorption of sulfate directly changed the dissolution path of the metal,which caused the subsequent passivation behavior of the alloy.Electrochemical studies in chlorine-containing solutions have shown that electrochemical tests show that the alloy has excellent corrosion resistance to the corrosion of chlorine-containing solutions.The main type of corrosion morphology is intergranular corrosion.The composition of the passivation film is significantly different from that in an acidic environment,and has a large number of atomic metal elements.electrochemical impedance spectroscopy studies of samples subjected to immersion tests have shown that environments containing chloride anions can cause degradation of the passivation film.But this destruction process takes some time,which may be directly related to the high resistance to pitting corrosion.